Consider the following possible class intervals for use in constructing a frequency distribution of serum cholesterol levels of subjects who participated in a mass screening:

(a) 50–74

(b) 50–74

(c) 50–75 75–99 75–99 75–100 100–149 100–124 100–125 150–174 125–149 125–150 175–199 150–174 150–175 200–249 175–199 175–200 250–274 200–224 200–225 etc. 225–249 225–250 etc. etc.
Which set of class intervals do you think is most appropriate for the purpose? Why? State specifically for each one why you think the other two are less desirable.